Cholecystokinin effects on feeding, glucose, and pancreatic hormones in rhesus monkeys

The effects of cholecystokinin on feeding, and on plasma glucose and pancreatic hormone responses to a mixed-meal were determined in lean rhesus monkeys. Following an overnight fast the octapeptide of cholecystokinin (CCK-8) was administered intravenously over a 6 minute period coincident with the initiation of free feeding or an intragastric infusion of a mixed liquid diet. CCK-8 inhibited feeding and delayed the plasma glucose and insulin response to a mixed-meal. The threshold for the feeding effect ranged from 30 to 120 ng/kg/min across monkeys and did not extend beyond 15 minutes of the start of the CCK infusion. The delays in plasma glucose and insulin were not dependent on rate or amount of food entering the stomach. Further, there were no alterations from basal levels in plasma glucose or insulin prior to the onset of CCK-induced feeding inhibition. There was no evidence that CCK-8 stimulated insulin release, nor was the usual close relationship between plasma glucose and insulin levels in response to a mixed-meal changed by CCK-8.